Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <cstdio>
#include <queue>
using namespace std;
int h, w, cnt, b[55][55];
char a[55][55];
queue<int> qr, qc;

void f(int p, int q, int r) {
	if(a[p][q]=='.') {
		qr.push(p);
		qc.push(q);
		a[p][q] = 'x';
		b[p][q] = r;
	}
}

int main() {
	int i, j;
	scanf("%d%d", &h, &w);
	for(i=1; i<=h; i++) {
		scanf("%s", &a[i][1]);
		for(j=1; j<=w; j++) cnt += a[i][j]=='.';
	}
	f(1, 1, 1);
	while(!qr.empty()) {
		i = qr.front(), qr.pop();
		j = qc.front(), qc.pop();
		if(i==h && j==w) {printf("%d", cnt-b[h][w]); return 0;}
		f(i+1, j, b[i][j]+1);
		f(i-1, j, b[i][j]+1);
		f(i, j+1, b[i][j]+1);
		f(i, j-1, b[i][j]+1);
	}
	puts("-1");
	return 0;
}